Electrochromic glazings include electrochromic materials that are known to change their optical properties, such as coloration, in response to the application of an electrical potential. For example, the glazing may become more or less transparent or more or less opaque. Typical electrochromic devices include a counter electrode layer, an electrochromic material layer which is deposited substantially parallel to the counter electrode layer, and an ionically conductive layer separating the counter electrode layer from) the electrochromic layer respectively. In addition, two transparent conductive layers are substantially parallel to and in contact with one of each the counter electrode layer and the electrochromic layer. Materials for making the counter electrode layer, the electrochromic material layer, the ionically conductive layer and the conductive layers are known and described, for example, in U.S. Pat. No. 7,372,610, incorporated by reference herein, and desirably are substantially transparent oxides or nitrides.
When an electrical potential is applied across the layered structure of the electrochromic device, such as by connecting the respective conductive layers to a low voltage electrical source, ions, such as Li+ ions stored in the counter electrode layer, flow from the counter electrode layer, through the ion conductor layer and to the electrochromic layer. In addition, electrons flow from the counter electrode layer, around an external circuit including a low voltage electrical source, to the electrochromic layer so as to maintain charge neutrality in the counter electrode layer and the electrochromic layer. The transfer of ions and electrons to the electrochromic layer causes the optical characteristics of the electrochromic layer, and optionally the counter electrode layer in a complementary EC device, to change, thereby changing the coloration and, thus, the transparency of the electrochromic device.
When installing electrochromic glazings, installing wires for power and control through the building's window framing system and the building's structural systems/supports can be difficult and costly. It is believed that a well-designed wireless controller coupled with photovoltaic cells can dramatically reduce the cost and complexity of installation, especially for architectural retrofit applications. The combination of photovoltaics and electrochromics provides excellent synergies, with tinting generally required only in daylight. Designing such a product for ease of manufacture and installation presents many challenges, given the diversity of framing systems and stringent aesthetic requirements of architects. To complicate matters, electronics should be replaceable without replacing or deglazing the unit and, if a battery is used, it also needs to be user replaceable.
Some electrochromic glazings are powered by solar-energy with or without battery back-up. Solar energy power sources, such as photovoltaic (solar) cells, and battery power sources come in a variety of sizes and power capacities. It is believed that the largest available solar cells and/or batteries are used to power a glazing may be too physically large or costly for relatively small scale applications. Furthermore, it may be costly to custom make solar panels for any given size as needed. Using a standard sized solar panel for a range of devices may be suitable from a power requirements standpoint, but the appearance of such a solar panel may not be aesthetically acceptable. There is, therefore, a needed for a solution that provides solar power (and battery power) devices that are scalable both in terms of power capacity and size and that are further suitable for a range of different sized and/or shaped glazings, without requiring custom design or manufacture.